The present invention relates to starter motors and more particularly to an electrically commutated coaxial starter motor for use with internal combustion engines.
Internal combustion engines of the type typically used for powering lawn mowers, pumps, generators, outboard motors, automotive engines and the like have conventionally utilized electric starter motors having gearing for driving the flywheel when starting the engine. A disengaging mechanism is also typically utilized to disconnect the starter motor from the engine after engine start up. Such engines also typically utilize alternators separate from the starter motor. A friction brake which engages the flywheel or a combination brake-clutch for a rotating blade is provided for safety purposes in lawn and garden or construction applications. It is thus desirable to provide a solid state device that provides a combination electric starter motor and alternator for automotive applications and a brake for lawn and garden applications employing internal combustion engines that eliminates the conventional gearing, separate alternator and brake.
It is known in brushless direct current motors to include a permanent magnet rotor, at least a pair of angularly spaced field windings surrounding or adjacent to the rotor, and means for controlling the commutation of current through the field windings in such a way that a rotating magnetic field is created to induce torque into the rotor and to cause it to rotate. In fact, various techniques have been employed to sense the angular position of the rotor with respect to the field windings. These techniques include employing the use of inductors, photoelectric devices, and magnetic sensors of the type shown in the following U.S. Patents:
______________________________________ U.S. Pat. No. Inventor Issue Date ______________________________________ 2,705,770 Suhr April 5, 1955 3,375,422 Boudigues March 26, 1968 3,453,514 Rakes et al July 1, 1969 3,531,702 Hill Sept. 29, 1970 3,667,018 Rakes May 30, 1972 3,714,532 McCurry Jan. 30, 1973 3,900,780 Tanikoshi Aug. 19, 1975 4,455,514 Ohno June 19, 1984 4,460,856 Mizumoto July 17, 1984 4,472,665 Tanikoshi Sept. 18, 1984 4,475,068 Brailsford Oct. 2, 1984 ______________________________________